…eturn type that is not a constructor returns "void" in the generated output. This fixes issue 969

-Modified SampleFileWriter_Code.ump so that expected and actual output is compared properly during assertUmpleTemplateFor(). This fixes issue 984, but is included in this commit because the fix is also necessary to fix issue 969 as the two issues share many test cases (JUnit can't be green for either issue unless they are both fixed).

…issue 969 (984 and 969 don't need to be worked on together after all).

… Java sense of the term) are correctly generated by Umple.

- Removed the "is this a main method check" from UmpleInternalParser_CodeClass.ump. Since what it means to have a "main function" varies from language to language (e.g. compare Java where the main method is the main entry point into a program and PhP where it's just another method) this check should be done and the results processed during code generation.
- Changed the "is this a main method check" in class_MethodDeclaration.ump to include a check for "void" and "String[] args"
- Added several new test cases to verify the main check and subsequent code generation is behaving correctly
- Added a "tearDown" method to DistributedClassTest.java that cleans up the mainMainClass static variable before moving to the next test set. Without the tearDown method the state from DistributedClassTest.java was being carried over to JavaClassTemplateTest.java, which was causing intermittent code generation issues.

… the user explicitly includes "void" in the .ump file.

…erated3.ump (it was identical to ClassTemplateTest_Generated2.java.txt and ClassTemplateTest_Generated2.ump